As you can see, modules have names and can be nested. If you use dots in module names, typescript will compile this to nested modules as follows:

module A.B.C {
export var x = 1;
}

This is equal to

module A {
module B {
module C {
export var x = 1;
}
}
}

What's also important is that if you reuse the exact same module name in one typescript program, the code will belong to the same module. Hence, you can use nested modules to implement hierarchichal namespaces.

There is no 'namespace' keyword, but internal modules (using the 'module' keyword) and external modules (using the 'export' keyword) offer a similar way to partition your code into logical hierarchies.